A conventional brake pressure control device for a vehicle is disclosed in Japanese Patent Laid Open No. 8(1996)-133059. The brake pressure control device disclosed in this publication includes a master cylinder, a pressure control valve, and a changeover valve disposed between the master cylinder and the pressure control valve. The changeover valve is designed to be switched to connect the master cylinder and the suction port of a fluid pump to supply brake fluid to each of the wheel brakes from the master cylinder when the brake pedal is not operated.
This conventional brake pressure control device is applied to a diagonal dual brake circuit mainly installed on a front engine front wheel drive vehicle having a pair of brake circuits, one of which is connected to the front right wheel brake and the rear left wheel brake and the other one of which is connected to the front left wheel brake and the rear right wheel brake.
When the above described device is applied to a front-rear dual brake circuit that is primarily installed on a front engine rear drive vehicle having a pair of circuits, one of which is connected to the front wheel brakes (front brake circuit) and the other one of which is connected to the rear wheel brakes (rear brake circuit), the brake pressure increase rate generated by the fluid pump differs between the front brake circuit and the rear brake circuit because brake fluid consumption differs between the front wheel brake and the rear wheel brake. Therefore, vehicle passengers may feel uncomfortable by the brake force difference between the front and rear of the vehicle.
If two fluid pumps each having a different capacity are applied to the front brake circuit and the rear brake circuit to address the foregoing drawback, the cost of the overall brake pressure control device is significantly increased.
In light of the foregoing, a need exists for a brake pressure control device that is not susceptible to the disadvantages and drawbacks associated with other known brake pressure control devices.
It would be desirable to provide a vehicle brake pressure control device that is able to equalize brake pressure differentials between the front brake circuit and the rear brake circuit.